1. Field of the Invention
The present invention relates to a battery module, and more particularly, to a battery module having an improved structure in which rechargeable batteries are electrically connected to each other.
2. Description of the Related Art
Rechargeable batteries can be repeatedly charged and discharged, unlike primary batteries that cannot be repeatedly charged. Low-capacity rechargeable batteries are used for portable compact electronic apparatuses such as mobile phones, notebook computers, and camcorders, and high-capacity rechargeable batteries are widely used as a power source for driving a motor of a hybrid vehicle, etc.
A high-output rechargeable battery using a non-aqueous electrolyte having high energy density has been developed in recent years. The high-output rechargeable battery is configured with high capacity by connecting a plurality of rechargeable batteries in series so as to be used for driving a motor for an apparatus requiring a large amount of power, i.e., an electrical vehicle, etc.
Furthermore, one high-capacity rechargeable battery is constituted by a plurality of rechargeable batteries which are connected to each other in series. The rechargeable batteries may have a cylindrical shape, a prismatic shape, and so forth.
The prismatic-shaped rechargeable battery includes an electrode assembly which has a positive electrode and a negative electrode with a separator interposed therebetween, a case having a space incorporating the electrode assembly, a cap plate which seals the case and has a terminal hole into which an electrode terminal is inserted, and an electrode terminal which is electrically connected with the electrode assembly and is inserted into the terminal hole to protrude outside of the case.
The rechargeable batteries are electrically connected with each other by a connection plate to constitute a battery module. The electrode terminal is fixed to the cap plate by a nut coupled to an upper portion of the electrode terminal, the connection plate is joined onto the nut, and the nut is joined onto the connection plate, such that the connection plate and the electrode terminal are electrically connected to each other.
However, a structure of fixing the connection plate with the nut is vulnerable to external vibration or shock. That is, when the nut is loosened by vibration or shock, electrical contact between the electrode terminal and the connection plate is deteriorated.
In order to solve the above-mentioned problem, a structure is proposed in which the electrode terminal is formed in a plate shape and the connection plate is fixed to the electrode terminal by welding, etc. However, this structure has a difficulty of welding each electrode terminal. Furthermore, after the connection plate is installed in the electrode terminal, the welding is performed. At this time, a jig for fixing the connection plate to the electrode terminal must be installed. As such, when each electrode terminal is welded in a state in which the jig is installed, the process is complicated and productivity is deteriorated.
In addition, the electrode terminal and the connection plate use materials having high electrical conductivity in order to suppress generation of heat and minimize loss of electric power. However, since these materials have high thermal conductivity as well as high electrical conductivity, welding heat is too rapidly transferred, such that the welding is very difficult and the quality of the welded part is deteriorated. In particular, when the welding is performed by a comparatively easy resistance welding scheme, resistance is small and transfer of the heat is rapid, such that the welding becomes very difficult. If arc welding or the like, other than resistance welding, is adopted, the transfer of the heat is rapid, such that melting does not normally occur and the welding process becomes inefficient.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.